Reaction calorimeters are used, among other purposes, for the determination of chemical and/or physical parameters of a sample. The use of a fast and efficient temperature control device is important in particular for the investigation of temperature-critical samples. In temperature-critical samples it is possible that changes of the composition, structure or other chemical and/or physical properties may occur even as a result of minor temperature fluctuations. An exemplary reaction calorimeter with a temperature control device is disclosed for example in WO 02/21089 A1.
The known state of the art includes different types of reaction calorimeters. These consist in most cases of a container or reactor for the reaction medium which can be heated or cooled by an attached temperature control device. A jacket that is filled with a temperature-control liquid and envelops the reactor is frequently used for this purpose. The temperature-control liquid is connected to a heat exchanger, so that the temperature of the temperature-control liquid can be regulated.
A reaction calorimeter with a capability of recording infrared spectra is described in A. Zogg et al., Ind. Eng. Chem. Res. 2003, 42, 767-776. The reactor is in this case embedded in a metal block which consists of a metal with a good thermal conductivity. The metal block is surrounded by Peltier elements which are connected to their electrical supply source in such a way that they can heat as well as cool the metal block. To conduct away heat in a cooling mode, the Peltier elements are connected to a cryostat. The cryostat contains a coolant whose temperature is regulated depending on the desired heat transfer rate. In order to enable this calorimeter to be operated in a power compensation mode, there is in addition a calibration heater arranged directly in the reactor. This calorimeter is suitable primarily for small sample volumes not exceeding about 50 ml.
The reaction calorimeters described above have the disadvantage that they cover only a relatively small temperature range from about −30° C. to about +150° C. and, further, that a large, voluminous and powerful electric supply is required, with the result that the control of the internal reactor temperature becomes cumbersome and slow. The limits of the temperature range are determined in particular by the initial temperature of the coolant. The temperature control devices and/or Peltier elements that are used can change the reactor temperature only by a certain amount in relation to the coolant temperature, and this amount may differ between the cooling mode and the heating mode. In addition, for example, the calorimeter described by Zogg et al. is designed only for small sample volumes.
Particularly in processes whose purpose is not limited to the controlled heating or cooling of a sample but extends to the determination of chemical and/or physical parameters, demanding requirements are imposed on the capability, the accuracy and the operative temperature range of the temperature control device. These requirements, which besides fast and efficient temperature control over a wide temperature range also include the size and compact design of the thermostat as well as cost-effectiveness and efficient use of resources, are difficult to realize particularly for larger sample volumes. For example in laboratory applications, it would be desirable to be able to use the same thermostat for the temperature control of sample volumes of a few microliters up to several hundred milliliters.
Therefore, an object of the present invention is to develop a calorimeter with an improved temperature control device, which device ensures a fast and efficient temperature regulation for sample volumes up to several hundred milliliters over a wide temperature range, and which can at the same time be made in a compact design and at a favorable cost.
This task is solved by a calorimeter with the capability to regulate an internal reactor temperature as well as by a temperature control device for a calorimeter according to the invention.